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What Is Slow-Wave Sleep?

The health benefits of sleep are sometimes ignored. As you get busy, you go to bed later or get up earlier, thinking you can make up the deficit on the weekend. When compared with other stages of sleep, a chronic lack of slow-wave sleep can do the most serious damage to your health. Understanding the sleep cycle, including slow-wave sleep, can help you make better decisions about your sleep habits.

  1. Definition

    • Slow-wave sleep, also called "deep sleep," is non-rapid eye movement sleep and is characterized by a significant drop in the frequency of brain waves. The deepest, most restorative sleep, slow-wave sleep makes up about 20 percent of total sleep time, according to WebMD. Slow-wave sleep includes NREM stages three and four, during which very slow delta waves are the primary electrical activity recorded in the brain.

      Slow-wave sleep plays a critical role in restoring your physical energy. According to HelpGuide.org, slow-wave sleep helps stimulate growth and development, gives your body a chance to repair damaged muscle and tissue and boosts your immune system. The site describes stage-three sleepers as being hard to wake up and "groggy and disoriented" if awakened. During stage four, when delta waves are an even higher percentage of brain activity, physical energy is restored as blood is directed toward the muscles.

    Sleep Architecture

    • The term "sleep architecture" refers to the patterns that occur as you move through a night's sleep. If you were to examine a graphic representation of your brain activity during sleep, you'd see periods of NREM sleep, during which brain waves decrease then increase in speed, followed by periods of REM, or rapid eye movement, sleep. You'd also see that the most frequent and longest periods of slow-wave sleep occur during the first half of the night.

      As you progress through NREM sleep and then REM sleep, you complete a sleep cycle. In a normal night's sleep, WebMD says, REM sleep occurs about every 90 minutes.

    Sleep Deprivation

    • Chronic sleep deprivation can have serious health implications. Dr. Timothy Morgenthaler, a sleep specialist at the Mayo Clinic, says people who don't get enough sleep have weaker immune systems and are more likely to get sick after virus exposure than those who get more sleep. Long-term effects of sleep deprivation include fatigue, mood disorders and obesity. You might experience mental impairment, such as a lack of creativity, difficulty making decisions or problems with memory and concentration. In addition, sleep deprivation places you at increased risk for heart disease, diabetes and injury.

    Getting Enough Sleep

    • Make an effort to go to bed about the same time each night and get up about the same time each morning, allowing yourself seven to nine hours to sleep. If after doing so, you're still struggling to get out of bed, talk to your doctor about participating in a sleep study to analyze your sleep and diagnose possible disorders such as sleep apnea. During the study you'll sleep at a sleep center or hospital where a technician will conduct polysomnography. MayoClinic.com says this test records sleep architecture, blood-oxygen levels, heart and respiration rates and eye and leg movements. A doctor who specializes in sleep will review the results of the study and, if necessary, recommend treatment such as continuous positive airway pressure.

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